Low voltage light tubing of the type described in the aforementioned patent has been widely used for safety and decorative purposes in hotels, restaurants, dance facilities, amusement parks and residences. In recent years, outdoor applications of such light tubing has increased, particularly at amusement parks to decorate roller coaster tracks and other thrill rides, where considerable vibration and shock forces are encountered, along with rain, wind, humidity, and temperature extremes.
Normally the low voltage miniature lamps, which are of the T-1 or "175" type commonly used for aircraft instrument panel illumination in small indicator displays such as red warning lights and the like, have an extremely long operating life. At the recommended six volts, these lamps consume less than one watt of power and have a rated operating life of more than 10,000 hours. Thus the lamps practically never burn out so the tubing seldom needs replacement under ordinary circumstances. However, the tubing used at amusement parks and in similar outdoor applications was found to require much more frequent repair or replacement. Apparently vibration and shock caused the lamps and connecting wires to move around within the tube rubbing against one another thus scraping off the insulative coating on the connecting wires to produce a short circuit. Also the thin wire leads on the lamps and the weld or solder connections on the ends would sometimes break. Where the tubing was placed underwater or exposed to rain, humidity and sudden temperature variations, moisture might enter the tubes causing corrosion of the wire leads or short-circuiting. In other instances, because the lamp filaments themselves become somewhat brittle with age, vibration and shock forces banging the lamps against the tube walls would break the filament.